I installed the Office 2016 patches. KB5001997, KB5002005, KB5002003 and now my Firefox icon on the quick launch keeps disappearing (showing only the blank icon). When I open Firefox it re-appears, then disappears a couple minutes later.

As well as the disappearing Firefox icon office apps started getting unresponsive, and every time I opened an office file it opened it in a new instance of the program, so open 1 excel file, have two instances of excel running.

Uninstalling KB5002005 resolved the issues.